I think one of the most important strengths of democracy is voting out people we don’t like, and MMP badly breaks that ability.
The argument for the list is when 5% of the population would vote for NZ First, and Winston Peters would get a seat because he put himself first on his party list. He would get over-representative power when a coalition government was required: in that specific situation he had a constituency. However in the larger parties (National, Labour) there are situations where people on their list get in on their party vote, even though the person is wildly disliked in the electorates, and would never get a constituency. During a past landslide Labour win, a bunch of nobodies wayyyy down the list (not expected to ever win) got in as members of parliament with zero constituency.
Very much so, and there is evidence that proportional systems produce, among modern democracies, better satisfaction of the electorate with government, richer political dialogue with more axes of variation.
> Most issues that voters care about are not local issues
That’s very much not true, but in the US system, more local issues tend to be the focus of more local governments (not always, but usually.) At the same time, local impacts of national issues are important and need representation, but proportional representation can be done in ways which respect that.
> Why do need a system to carve up representation along geographical boundaries?
Several reasons: representation of local concerns, accountability of individual representatives to the general electorate and not just a party, and providing individual citizens at least one representative that clearly and concretely represents them particularly, not just their party of preference.
But you can do PR with local district representatives. Two key methods which do this:
Single Transferrable Vote (STV; the multiwinner analog of Instant Runoff Voting/Ranked Choice Voting) provides proportional representation by district in multimember districts, which provides coarse-grained proportionality overall while providing local representation, and mitigating the impact of specific districting decisions, since its very hard for them to have any significant effect on partisan representation overall.
Mixed Member Proportional, in which people have two ballots for a legislative body, one for a district elections (which can be single-winner FPTP, multiwinner STV, or just about anything else), and one for a party. The winners of the district elections are elected, but in the same body enough additional seats are added, from party lists, to achieve proportionality (within the tolerances specified in the system) overall, by reference to the party votes in the second ballot.
STV is the most straightforward and the one that would probably be least problematic for US state or federal legislative elections. (Federally, it would require a change to statute to either allow or mandate states to use it, because there is a statutory single-member-district mandate currently.)